
   Drilbo (Drilbo Represents an Imaging Libary not only for Blorb Objects) is
   the imaging support library for the fizmo interpreter. It supports the
   following file input formats:
    - JPEG
    - PNG
    - Z-Machine V6 graphics, MG1 format

   Not supported:
    - Z-Machine V6 graphics, Amiga and Macintosh format

   The following file output formats are supported:
    - JPEG in RGB, Grayscale and JCS_YCbCr.
    - PPM, P6 variant (usually for testing purposes, P3 variant available,
      but outcommented in the code).

   The following screen output methods are supported:
    - X11 display though XLib, Truecolor only.

   These imaging operations are implemented:
    - Bilinear scaling

   All operations use a "z_image" type which holds all the data and metadata
   for images. A z_image may contain either an RGB or a grayscale file with a
   depth of 8 bit per pixel.

   See "drilbo.h" for more information on the specific functions.

   ---

   From The Z-Machine-Specification, section 8 (just for reference):

   Some details of the known IBM graphics files are given in Paul David
   Doherty's "Infocom Fact Sheet". See also Mark Howell's program "pix2gif",
   which extracts pictures to GIF files. (This is one of his "Ztools"
   programs.)

   Although Version 6 graphics files are not specified here, and were
   released in several different formats by Infocom for different computers,
   a consensus seems to have emerged that the MCGA pictures are the ones to
   adopt (files with filenames *.MG1). These are visually identical to Amiga
   pictures (whose format has been deciphered by Mark Knibbs). However, some
   Version 6 story files were tailored to the interpreters they would run on,
   and use the pictures differently according to what they expect the
   pictures to be. (For instance, an Amiga-intended story file will use one
   big Amiga-format picture where an MSDOS-intended story file will use
   several smaller MCGA ones.)

   The easiest option is to interpret only DOS-intended Version 6 story files
   and only MCGA pictures. But it may be helpful to examine the Frotz source
   code, as Frotz implements draw_picture and picture_data so that Amiga and
   Macintosh forms of Version 6 story files can also be used.

   It is generally felt that newly-written graphical games should not imitate
   the old Infocom graphics formats, which are very awkward to construct and
   have been overtaken by technology. Instead, the draft Blorb proposal for
   packaging up resources with Z-machine games calls for PNG format graphics
   glued together in a fairly simple way. An ideal Version 6 interpreter
   ought to understand both the four Infocom picture-sets and any Blorb set,
   thus catering for old and new games alike.

